Field of the Invention
The present invention relates to a handheld device, a base station and transmission control methods thereof. More particularly, the handheld device of the present invention transmits an uplink signal with an uplink dedicated physical control channel (UL DPCCH) to a base station and utilizes parts of the TFCI fields of the UL DPCCH to carry acknowledgement (ACK) information for downlink data frame early termination.
Descriptions of the Related Art
With the development of wireless communication technologies, wireless devices have been widely used. To satisfy users' demands for communication, various telecommunication standards have been developed. Universal mobile telecommunications system frequency division duplex (UMTS-FDD) Release 99 is a version of the third generation (3G) communication system. The UMTS-FDD Release 99 provides circuit-switched speech services in which a circuit-switched connection is established between a user device and a base station. User data and physical layer control information are carried on dedicated physical channels (DPCHs) of the uplink signal and the downlink signal, and the uplink signal and the downlink signal are respectively transmitted in different frequency bands at the same time.
FIG. 1A is a schematic diagram of the uplink signal in a radio frame with 15 slots as defined in the UMTS-FDD Release 99 specification. The DPCH of the uplink signal includes a dedicated physical data channel (DPDCH) carrying the user data and a dedicated physical control channel (DPCCH) carrying physical layer control information. In each slot, the DPCCH comprises a pilot field, a transport format combination indication (TFCI) field, a feedback indication (FBI) field and a transmit power control (TPC) field. In addition, the minimum transmission time interval (minimum TTI) defined in the UMTS-FDD Release 99 specification may be one, two or four radio frames. In the case that the minimum TTI is two or four radio frames, the first 30 bits of the TFCI code word are repeatedly carried in each radio frame in the minimum TTI. For example, FIG. 1B depicts the repeated TFCI code word where the minimum TTI is two radio frames.
Furthermore, in the UMTS-FDD Release 99 system, the downlink data frame of the downlink signal simultaneously received by the user device is encoded with an appropriate code rate. In such a case, the encoded downlink data frame may be successfully decoded by the user device without the need of thoroughly receiving the whole downlink data frame within the minimum TTI. Thus, the remaining part of the downlink data frame may not have to be received by the user device and transmitted by the base station. In view of the aforesaid, the current transmission mechanism in UMTS-FDD Release 99 system likely has unnecessary power consumption in the base station. In addition, the base station cannot be immediately informed if the downlink data frame has been successfully and early decoded. As a result, the base station cannot terminate the transmission of the downlink data frame, reallocate the transmission power of different downlink signals for multiple user devices and reduce the interference among the downlink signals.
Accordingly, it is important to provide a transmission mechanism which can immediately inform the base station that the downlink data frame of the downlink signal has been successfully and early decoded to make the base station capable of terminating the transmission of the downlink data frame, reallocating the transmission power of different downlink signals for multiple user devices and reducing the interference among the downlink signals.